Research unravels genetic ancestry of the strawberry

After four years of research, scientists from the University of New Hampshire (UNH) have unlocked a major genetic mystery of one of the ancestors of cultivated strawberry, known as Fragaria iinumae. Through their work with Fragaria iinumae, they will be able to better understand the cultivated strawberry, which is known as one of the most genetically complex plants.

“Many people are trying to understand the ancestry of the cultivated strawberry so that they can better understand traits associated with specific genetic markers, such as fruit quality, flowering habits, and resistance to diseases,” researcher Lisa Mahoney said. “Defining the genomes of the cultivated strawberry’s wild ancestors will ultimately help guide the use of genetic information in breeding for a better cultivated strawberry.”

An article based on the research explains that the researchers involved constructed a linkage map of the seven chromosomes of the diploid Fragaria iinumae, which allows them to fill in a piece of the genetic puzzle about the eight sets of chromosomes of the cultivated strawberry. The cultivated strawberry is believed to trace its genetic ancestry to as many as four diploid ancestral strawberries, one of which is Fragaria iinumae.

The research on Fragaria iinumae is the second time experiment station researchers have mapped the genes of an ancestral diploid strawberry of the cultivated strawberry. In 2011, UNH researchers were part of a team that sequenced Fragaria vesca, another diploid ancestor of the cultivated strawberry. This reference sequence immediately became an indispensable resource in strawberry genetic research throughout the world.

“This remarkable genetic map, which is the highest resolution linkage map for any ancestral diploid strawberry species, is a valuable research tool in and of itself. More importantly, it provides a necessary resource for assembly of a Fragaria iinumae reference genomic sequence as a much needed complement to the previously published reference genome for ancestral diploid Fragaria vesca,” Mahoney said in the article.

To create the genetic map of Fragaria iinumae, experiment station researchers used the IStraw90® strawberry SNP array, an advanced genomics tool for marker-assisted mapping. Prior to the advent of the marker-assisted mapping approach, breeders had to rely only on the evaluation of physiological traits such as fruit yield, disease resistance, and flavor for hundreds of plants to identify those with the desired traits, while having little or no knowledge of each plant’s underlying genetic composition. The evaluation of traits in very large breeding populations is costly and time-consuming.

The U.S. is the world’s leading producer of strawberries. According to the USDA, the U.S. produced more than 3 billion pounds of strawberries in 2012, valued at $2.4 billion. The article explains that most U.S. strawberries are grown in California but are also an important crop in New Hampshire.